--- title: "A case for weak dependencies in JavaScript" publication: "JavaScript Weekly" issue: 515 published_at: "2020-11-20" canonical_url: "https://javascriptweekly.com/issues/515" --- Plus TypeScript 4.1, Prettier 2.2, and how to use npm packages on CodePen. #515 — November 20, 2020 [Unsubscribe](https://javascriptweekly.com/leave/*|UID|*)|[Read on the Web](https://javascriptweekly.com/issues/515) JavaScript Weekly [![\](https://res.cloudinary.com/cpress/image/upload/w_1280,e_sharpen:60/v1605891954/wpip59mgcqxzixazms8d.png)](https://devblogs.microsoft.com/typescript/announcing-typescript-4-1/) [TypeScript 4.1 Released](https://devblogs.microsoft.com/typescript/announcing-typescript-4-1/) — The ever popular ‘JavaScript with types’ takes more steps forward with template literal types, key remapping in mapped types, recursive conditional types, and support for React 17’s `jsx` and `jsxs` factory functions. If you’re a _Create React App_ user though, don’t rush to upgrade just yet as a few issues have been noted. Daniel Rosenwasser (Microsoft) [A Tale of Going from JavaScript to WebAssembly](https://engineering.q42.nl/webassembly/) — A developer of a ‘ultra resolution’ storytelling platform tells the tale of upgrading their Web client’s performance by moving from a pure JavaScript approach to one turbocharged with WebAssembly. There’s a lot to learn here. Marcel Duin [![\](https://copm.s3.amazonaws.com/c0d5aca9.png)](https://blog.newrelic.com/product-news/monitor-frontend-performance-with-user-centric-performance-metrics/?utm_campaign=FY21-Q3-DEV-OBSV-AMER-JSW-NL-None-B_MFEP&utm_medium=NL&utm_source=JSW&utm_content=B_MFEP&fiscal_year=FY21&quarter=Q3>m=DEV&program=OBSV&ad_type=None&geo=AMER) [Monitor Frontend Performance With User-Centric Metrics](https://blog.newrelic.com/product-news/monitor-frontend-performance-with-user-centric-performance-metrics/?utm_campaign=FY21-Q3-DEV-OBSV-AMER-JSW-NL-None-B_MFEP&utm_medium=NL&utm_source=JSW&utm_content=B_MFEP&fiscal_year=FY21&quarter=Q3>m=DEV&program=OBSV&ad_type=None&geo=AMER) — Traditional metrics like page load aren’t enough to guarantee that you're providing a solid user experience. Learn to track interactivity metrics like “firstInteraction” so you can build for better impact, and keep users coming back. New Relic sponsor [Prettier 2.2 Released](https://prettier.io/blog/2020/11/20/2.2.0.html) — The popular opinionated code formatter gains TypeScript 4.1 support, comes as ES modules so you can use it directly within the browser, and supports two new JavaScript parsers: [espress](https://github.com/eslint/espree) and [meriyah.](https://github.com/meriyah/meriyah) Sosuke Suzuki [Electron 11 Released with Experimental Apple Silicon Support](https://www.electronjs.org/releases/stable#11.0.0) — The popular cross platform desktop app environment upgrades its dependencies across the board (hi Chromium 87!) and [begins to take steps](https://www.electronjs.org/blog/apple-silicon) into the Darwin arm64 world. GitHub / OpenJS Foundation **⚡️ Quick bytes:** - Chrome 87 has changed [how background tabs use resources](https://blog.chromium.org/2020/11/tab-throttling-and-more-performance.html) and JavaScript timer wakeups will [now be throttled](https://docs.google.com/document/d/11FhKHRcABGS4SWPFGwoL6g0ALMqrFKapCk5ZTKKupEk/view) to once per minute. - Firefox 83, released this week, brings [significant JS performance improvements](https://hacks.mozilla.org/2020/11/warp-improved-js-performance-in-firefox-83/) through an updated approach to JIT compilation. - An interesting [Twitter thread telling the story](https://twitter.com/frontstuff_io/status/1329553850693525505) of how so many tools and moving parts can make debugging seemingly straightforward issues seem like advanced plumbing. - _Smashing Magazine_ has [a new TypeScript book out](https://www.smashingmagazine.com/2020/11/typescript-in-50-lessons-release/) and they always make great stuff. - It's more [_Frontend Focus_](https://frontendfoc.us/?ref=jsw) territory but [Tailwind CSS 2.0 is out.](https://blog.tailwindcss.com/tailwindcss-v2) - Jordan Harband is [stepping down](https://twitter.com/ljharb/status/1328278033363476480) as editor of the JS spec once ES2020 is final early next year. 📚 Tutorials, Opinions and Stories [The Case for Weak Dependencies in JS](https://lea.verou.me/2020/11/the-case-for-weak-dependencies-in-js/) — If you’re using ES modules and want to check if one is present before using it in some optional way, what do you do? Lea explains why this would be useful and shares some ideas with how it could be implemented. Lea Verou [The Most Accurate Way to Schedule a Function in the Browser](https://medium.com/teads-engineering/the-most-accurate-way-to-schedule-a-function-in-a-web-browser-eadcd164da12) — A detailed analysis of three JavaScript timeout strategies and how they perform in thousands of web contexts. A bit of a micro-optimization for sure, but it’s interesting to dig into the weeds like this. Benoit Ruiz [10 React Security Best Practices](https://snyk.co/ucTIz) — A checklist to help you and your team find and fix security issues in your React applications. Snyk sponsor [Importing React Through the Ages](https://epicreact.dev/importing-react-through-the-ages/) — Kent looks at the wide variety of ways you can import React now and why he prefers a specific one. Kent C. Dodds [Creating WebGL Effects with CurtainsJS](https://css-tricks.com/creating-webgl-effects-with-curtainsjs/) — A way to add neat WebGL effects to and